Control of Electrically Interconnected Vehicular Suspension System

The escalating attention on ride comfort and safety in vehicles, driven by a surge in transportation time, underscores the critical role of vehicle suspension. This study focuses on electrically interconnected suspension (EIS), a burgeoning technology utilizing electrical components for enhanced flexibility and adaptability. The research aims to develop and validate effective EIS systems and control strategies to elevate ride comfort. The three types of suspension systems: passive, active, and semi-active, highlight the design challenges of balancing ride comfort, road handling, and suspension deflection limitations. The limitations of these systems, particularly active suspension\u27s drawbacks of high energy consumption and cost, prompt exploration of semi-active solutions such as EIS. An innovative EIS system is introduced, featuring variable inertance and variable damping (VIVD) in the heave direction and variable stiffness (VS) in the roll direction. Unlike traditional systems, this EIS achieves suspension interconnection through an electrical network (EN), offering enhanced design flexibility, energy efficiency, and rapid system response. Experimental validation on a half-car test rig demonstrates superior performance compared to passive suspension, emphasising its potential to enhance ride comfort. Further enhancing EIS performance, a disturbance compensation control strategy based on acceleration measurements is introduced. Disturbance observers, grounded in practical acceleration measurements, address challenges related to unknown disturbances, model simplification, and EN nonlinearity. Experimental results affirm the effectiveness of the proposed disturbance compensation controller, emphasising its promise for practical applications. In addition, a closed-loop current control unit (CCU) is designed to achieve precise and continuous current control for the EIS system. Employing high-frequency metal–oxide–semiconductor field-effect transistors (MOSFETs) and a resistor, the CCU enables dynamic resistance adjustment through a Pulse Width Modulation (PWM) signal. A robust sliding mode control strategy is implemented to address nonlinearities, forming a closed-loop CCU. Experimental validation demonstrates the CCU\u27s effectiveness in significantly enhancing vibration control performance, highlighting its potential contribution to EIS technology. Introducing known nonlinearity into vibration control systems has been proven to enhance performance. A novel nonlinear electromagnetic damper (EMD) integrated into decoupled EIS utilising the CCU has been proposed. The damper allows for the emulation of equivalent nonlinear mechanical properties in corresponding directions. Through dynamic resistance adjustment within the EN, damping can be continuously modulated based on arbitrary nonlinear functions related to suspension deflection or deflection rate. The proposed approach offers flexibility and effectiveness in achieving nonlinear damping with minimal structural constraints compared to other nonlinear damping/stiffness structures. Simulation results demonstrate significant improvements compared to passive systems. These findings offer valuable insights for designing nonlinear damping mechanisms to enhance vibration control performance in various engineering applications. The thesis concludes by summarizing the main contributions, including the development of a versatile semi-active EIS, decoupled control strategies, disturbance compensation methods, and an innovative closed-loop CCU. These advancements underscore the potential of EIS in revolutionizing vehicle suspension systems, particularly in achieving superior ride comfort in diverse and challenging conditions

Pretreatment Lymphocyte Monocyte Ratio Predicts Long-Term Outcomes in Patients with Digestive System Tumor: A Meta-Analysis

Purpose. The prognostic value of pretreatment lymphocyte monocyte ratio (LMR) in digestive system cancer patients remains controversial. The aim of this study was to quantify the prognostic impact of this biomarker and assess its consistency in digestive system tumors. Methods. We searched “PubMed,” “Embase,” and “CBM” for published eligible studies before June 2016 and conducted a meta-analysis to estimate the pooled hazard ratios (HRs) for disease recurrence and mortality focusing on LMR. Subgroup analyses, meta-regression, and sensitivity analyses were also performed. Results. A total of 22 cohort studies enrolling 12829 patients with digestive system cancer were included. The summary results showed that lower LMR was significantly associated with worse overall survival (OS), cancer-specific survival (CSS), and tumor disease or recurrence-free survival (DFS/RFS) in analyses using the studies reporting HRs either by the univariate analyses (HR = 1.32, HR = 1.35, and HR = 1.26 for OS, CSS, and DFS/RFS, resp.) or by multivariate analyses (HR = 1.21, HR = 1.18, and HR = 1.26 for OS, CSS, and DFS/RFS, resp.). Conclusion. Our results support the fact that decreased LMR indicates worse prognosis in multiple digestive system tumors

Intensity of Left Atrial Spontaneous Echo Contrast as a Correlate for Stroke Risk Stratification in Patients with Nonvalvular Atrial Fibrillation.

The intensity of left atrial spontaneous echo contrast (LASEC) by transesophageal echocardiography (TEE) has been proposed as an important variable in the stratification of thromboembolic risk, particularly in patients with nonvalvular atrial fibrillation (NVAF). We hypothesized that the quantification of LASEC by ultrasound will improve its utility in predicting subsequent stroke events in patients with NVAF. Patients (n = 206) with definite NVAF receiving TEE were included for this prospective cohort study. Baseline clinical risk factors of stroke, CHADS2 score and CHA2DS2-Vasc, left atrial thrombus (LAT), the five-grades of LASEC and video intensity (VI) value of LASEC were measured. During 2 years follow-up, 20 patients (9.7%) developed stroke. VI value of LASEC in the patients with stroke was higher compared to patients without stroke (25.30 ± 3.61 vs. 8.65 ± 0.81, p \u3c 0.001). On logistic regression analysis, LAT, qualitative LASEC, graded LASEC, VI value of LASEC and CHADS2 and CHA2DS2-Vasc score were independent predictors of stroke. Among them, the highest area under the curve of receiver operating characteristic (ROC) in predicting stroke was VI value of LASEC (p \u3c 0.05). These results show that quantification of LASEC by VI value is the most favorable predictor of stroke in patients with NVAF, and calls for improving the utility of LASEC in predicting subsequent stroke events

CFD-based Design Optimization of Ducted Hydrokinetic Turbines

Hydrokinetic turbines extract kinetic energy from moving water to generate renewable electricity, thus contributing to sustainable energy production and reducing reliance on fossil fuels. It has been hypothesized that a duct can accelerate and condition the fluid flow passing the turbine blades, improving the overall energy extraction efficiency. However, no substantial evidence has been provided so far for hydrokinetic turbines. To investigate this problem, we perform a CFD-based optimization study with a blade-resolved Reynolds-averaged Navier--Stokes (RANS) solver to explore the design of a ducted hydrokinetic turbine that maximizes the efficiency of energy extraction. To handle the high-dimensional design space of the blade and duct geometry, we use a gradient-based optimization approach where the gradients are computed using the adjoint method. The final design is re-evaluated through higher-fidelity unsteady RANS (URANS) simulations. Our optimized ducted turbine achieves an efficiency of about 54% over a range of operating conditions, higher than the typical 46% efficiency of unducted turbines such as the well-known Bahaj model

Use of a leaf chlorophyll content index to improve the prediction of above-ground biomass and productivity

Improving the accuracy of predicting plant productivity is a key element in planning nutrient management strategies to ensure a balance between nutrient supply and demand under climate change. A calculation based on intercepted photosynthetically active radiation is an effective and relatively reliable way to determine the climate impact on a crop above-ground biomass (AGB). This research shows that using variations in a chlorophyll content index (CCI) in a mathematical function could effectively obtain good statistical diagnostic results between simulated and observed crop biomass. In this study, the leaf CCI, which is used as a biochemical photosynthetic component and calibration parameter, increased simulation accuracy across the growing stages during 2016–2017. This calculation improves the accuracy of prediction and modelling of crops under specific agroecosystems, and it may also improve projections of AGB for a variety of other crops

A broad-spectrum gas sensor based on correlated two-dimensional electron gas

Designing a broad-spectrum gas sensor capable of identifying gas components in complex environments, such as mixed atmospheres or extreme temperatures, is a significant concern for various technologies, including energy, geological science, and planetary exploration. The main challenge lies in finding materials that exhibit high chemical stability and wide working temperature range. Materials that amplify signals through non-chemical methods could open up new sensing avenues. Here, we present the discovery of a broad-spectrum gas sensor utilizing correlated two-dimensional electron gas at a delta-doped LaAlO3/SrTiO3 interface with LaFeO3. Our study reveals that a back-gating on this two-dimensional electron gas can induce a non-volatile metal to insulator transition, which consequently can activate the two-dimensional electron gas to sensitively and quantitatively probe very broad gas species, no matter whether they are polar, non-polar, or inert gases. Different gas species cause resistance change at their sublimation or boiling temperature and a well-defined phase transition angle can quantitatively determine their partial pressures. Such unique correlated two-dimensional electron gas sensor is not affected by gas mixtures and maintains a wide operating temperature range. Furthermore, its readout is a simple measurement of electric resistance change, thus providing a very low-cost and high-efficient broad-spectrum sensing technique.</p

Patchouli alcohol improved diarrhea-predominant irritable bowel syndrome by regulating excitatory neurotransmission in the myenteric plexus of rats

Background and Purpose: Irritable bowel syndrome (IBS) is usually associated with chronic gastrointestinal disorders. Its most common subtype is accompanied with diarrhea (IBS-D). The enteric nervous system (ENS) modulates major gastrointestinal motility and functions whose aberration may induce IBS-D. The enteric neurons are susceptible to long-term neurotransmitter level alterations. The patchouli alcohol (PA), extracted from Pogostemonis Herba, has been reported to regulate neurotransmitter release in the ENS, while its effectiveness against IBS-D and the underlying mechanism remain unknown.Experimental Approach: In this study, we established an IBS-D model in rats through chronic restraint stress. We administered the rats with 5, 10, and 20 mg/kg of PA for intestinal and visceral examinations. The longitudinal muscle myenteric plexus (LMMP) neurons were further immunohistochemically stained for quantitative, morphological, and neurotransmitters analyses.Key Results: We found that PA decreased visceral sensitivity, diarrhea symptoms and intestinal transit in the IBS-D rats. Meanwhile, 10 and 20 mg/kg of PA significantly reduced the proportion of excitatory LMMP neurons in the distal colon, decreased the number of acetylcholine (Ach)- and substance P (SP)-positive neurons in the distal colon and restored the levels of Ach and SP in the IBS-D rats.Conclusion and Implications: These findings indicated that PA modulated LMMP excitatory neuron activities, improved intestinal motility and alleviated IBS-induced diarrheal symptoms, suggesting the potential therapeutic efficacy of PA against IBS-D